1. Technical Field
The present invention relates to a robot.
2. Related Art
In the past, industrial robots have widely been used for the purpose of automatization or laborsaving in operations such as an assembling process or a welding process of industrial products in manufacturing scenes such as factories. Further, in recent years, due to the fact that an operation process has been complicated in order to cope with miniaturization and increase in functionality of industrial products, there has been increasing the demand for robots with multiaxial control having an articulated arm including a plurality of members constituting a robot arm combined with each other so as to rotate relatively to each other using joint drive axes (rotational axes). In JP-A-2008-188699 (Document 1), for example, there is disclosed a dual-arm robot having six-axis articulated arms coupled on both sides of a base member (body). Such a six-axis articulated arm is composed of, for example, a shoulder section, an upper arm section, a forearm section, and a wrist section as members in order to realize a similar movement to the movement of a human arm. On the tip side of the member forming the wrist section of such an articulated arm, there is attached an end effector such as a robot hand for executing a predetermined operation to be performed by the robot.
In such a robot, there are installed cables for supplying power to electric motors forming drive sources of the members and the end effector connected adjacently to each other, and for transmitting and receiving control signals between the motors and a robot control section. As the wiring method in this case, there can be cited an internal wiring method for installing the cables inside the base member and the arm, and an external wiring method for installing the cables along the external surface of the robot, and it is conceivable that the internal wiring method is advantageous to the recent demand for the miniaturization of robots. In the wiring of the robot using the internal wiring method, it is required to adopt a wiring structure not hindering the relative rotational movement between the members (e.g., the base member and the arm, the arm and the arm, the arm and the wrist section) adjacent to each other and making a relative rotational movement in a joint section making a rotational movement.
In for example JP-A-2003-230223 (Document 2), there is introduced a wiring structure in which a first member and a second member making a relative rotational movement are connected to each other using a flat cable. Specifically, one end of the flat cable is connected to a first connector as a connection section provided to the first member, and the other end of the flat cable is connected to a second connector provided to the second member via a reel, which is provided to the second member, and around which the other end side of the flat cable is wound.
As described above, the flat cable having the both ends connected respectively to the first connector and the second connector can avoid such problems as breaking of wiring or early deterioration since a tensile force applied to the wiring is absorbed when the flat cable moves in a winding direction or a rewinding direction, in particular in the rewinding direction, following the relative rotational movement between the first member and the second member in the reel portion around which the flat cable is wound.
In JP-A-2010-214530 (Document 3), for example, there is introduced a wiring structure for a rotating joint (a rotary joint) in which in the wiring structure for connecting the first member and the second member making a relative rotational movement to each other using a flat cable (a flexible printed circuit (FPC) board), a flat cable having one end connected to the first member is connected to a core member in the other end side, a reel having a further part of the other end side of the flat cable wound around the core member outward is formed, and the other end of the flat cable is connected to the second member or the end effector coupled to the tip side of the second member via the reel.
According to this wiring structure, the flat cable connecting the first member and the second member to each other can avoid such problems as breaking of wiring or early deterioration since the tensile force applied to the wiring is absorbed when the flat cable moves in the winding direction or the rewinding direction, in particular in the rewinding direction, following the relative rotational movement between the first member and the second member in the reel portion around which the flat cable is wound.
However, in the internal wiring structure described in Document 2, the first connector and the second connector are disposed so that the inserting directions of the flat cable are opposed roughly in parallel to each other. Therefore, if a force in the tensile direction occurs in the flat cable in the connection section between each of the first and second connectors and the flat cable, it results that a force in a direction in which the flat cable is pulled out from the connector is applied, and therefore, there is a problem that a connection failure due to loose or dropout of the connection section of the flat cable might be incurred.
Further, in the internal wiring structure described in Document 2, in the case of adopting a configuration of installing a plurality of flat cables in an overlapping manner, since a large space for arranging a plurality of connectors in parallel to each other becomes necessary in each of the first connector side and the second connector side, there is a problem that it is disadvantageous to miniaturization of the robot.
Further, although not clearly described in the wiring structure of the robot described in Document 2, a relay board is provided with a third connector connected to the second connector, and the flat cable connected to the third connector is connected to the end effector (an operating member) to thereby constitute the wiring structure with the flat cable between the first member and the end effector via the relay board. By relaying the wiring between the first member and the end effector by the relay board in such a manner, complication of an arrangement of the flat cable and increase in cost due to increase in length of the flat cable can be avoided.
Here, in order to form the relay wiring structure of the flat cable using the relay board in the wrist section (the second member), in which the miniaturization is particularly marked due to progress in miniaturization of robots, it is necessary to devise an arrangement of the connectors provided to the relay board, arrangement paths of the flat cables connected to the connectors, and so on.
However, in the wiring structure of the robot described in Document 2, the arrangement of the connectors, the arrangement paths of the flat cables between the members and the operation sections are not clearly specified. Therefore, there is a problem that there is a possibility that it becomes difficult to incorporate the relay wiring structure into the second member, or the connection becomes unstable and the reliability is degraded due to an unreasonable arrangement of the flat cables.
In achieving the miniaturization of the robot having an articulated arm such as a six-axis arm, the miniaturization of the wrist section to which the end effector is attached on the tip side is a dominant factor. Therefore, in the wiring structure forming the reel described in Document 3, since the space for arranging the wiring on the operating member side of the reel is limited, it is necessary to devise the wiring paths.
However, since there is no specific description of the wiring path of the flat cable on the operating member side of the reel in Document 3, there is a problem that the arrangement path of the wiring using the flat cable on the foreside of the wrist section of the articulated arm becomes complicated, or it becomes necessary to perform a complicated work on the member of the wrist section in order to provide the wiring path.